landlock: Minor typo and grammar fixes in IPC scoping documentation

* Fix some whitespace, punctuation and minor grammar.
* Add a missing sentence about the minimum ABI version,
  to stay in line with the section next to it.

Cc: Tahera Fahimi <fahimitahera@gmail.com>
Cc: Tanya Agarwal <tanyaagarwal25699@gmail.com>
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20250124154445.162841-1-gnoack@google.com


[mic: Add newlines, update doc date]
Signed-off-by: Mickaël Salaün <mic@digikod.net>